| abstract |
Process for the preparation of alpha , beta -monoethylenic unsaturated aldehydes, carboxylic acids or nitriles containing 3 to 5 C atoms by catalytic gas phase oxidation or ammoxidation of a reduced form of the desired compound in a multitube fixed-bed reactor charged with catalytically active multimetal oxides, in which the volume-specific activity of the catalytic charge decreases abruptly, successively, stepwise and/or continuously along the contact tubes in the flow direction. |